JPH0552872B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical field of the invention] The present invention relates to a flexible printed wiring board,
An adhesive composition for flexible printed wiring boards that has strong adhesion between metal foil and thin synthetic resin material, excellent heat resistance and heat deterioration resistance, moisture resistance and flame retardancy, and has excellent processing properties. . [Technical Background of the Invention and Problems Therewith] In recent years, as electronic devices have become more dense, lighter, thinner, and smaller, there has been an increasing demand for lightweight, flexible printed wiring boards that can mount three-dimensional wiring or functions. In addition, in consumer electronics, from the viewpoint of safety in particular, demands for flame retardant materials and adhesive properties after heat deterioration are becoming stronger. Adhesives for flexible printed wiring boards are used not only to bond thin synthetic resin materials and the treated surface of metal foil, but also to insulate and protect circuits on the shear (polished) surface of the metal foil of patterned wiring boards. It is desirable that it can be used to adhere coverlay films for use in other applications. In particular, for coverlay film adhesion, it must be able to firmly adhere to the sheared surface of the metal foil, suppress flow to the land portion to a small amount, and have good embedding properties between pattern circuits. On top of that,
Shelf life is at least 1 month at room temperature and 3 months at 5°C.
More than a month is required. Furthermore, in order to improve productivity and maintain dimensional accuracy, there is a need for workability that allows for heating and compression bonding at low temperatures and in a short time. However, conventional adhesives for flexible printed wiring boards, even when polyimide film with excellent heat resistance and flame retardancy is used as the base thin material, have poor adhesion, heat resistance, line insulation resistance, and It has been extremely difficult to achieve both heat deterioration resistance and flame retardancy. Conventionally, as adhesives for flexible printed wiring boards, nitrile rubber adhesives (JP-A-51-135936, JP-A-57-3877),
Polyamide adhesive (JP-A-54-125285), polyester adhesive (JP-A-50-16866, JP-A-54-7441), polyacrylic adhesive (JP-A-54-125285)
54-162736) and many others have been proposed. However, the nitrile rubber type has the disadvantage that it has poor adhesion after heat-resistant aging and tends to become extremely hard after a 10-day air aging test at 150°C, and the polyamide type has the disadvantage of slightly high hygroscopicity. be. Polyester-based materials have the disadvantage of weak adhesive strength compared to polyimide films, and polyacrylic-based materials require high temperatures and long periods of time for heat molding, and when the molding temperature is lowered and the molding time is shortened, they have the disadvantage of poor moisture resistance. . [Object of the Invention] The object of the present invention has been made to solve the above-mentioned difficulties and disadvantages, and has excellent adhesiveness, heat deterioration resistance, flame retardance, and moisture resistance, and can be processed as a coverlay film adhesive. The present invention aims to provide an adhesive composition for flexible printed wiring boards with good properties. [Summary of the Invention] As a result of intensive studies aimed at achieving the above object, the present inventors have discovered that the adhesive composition described below is suitable as an adhesive for flexible printed wiring boards, and have arrived at the present invention. It is ivy. That is, the present invention provides (A) an acrylic elastomer having one or more functional groups selected from the group of epoxy groups, carboxyl groups, and hydroxyl groups, (B) polyparavinylphenol resin, and (C) epoxy resin. , (D) a polyester urethane resin, (E) a curing agent accelerator, and (F) an inorganic filler as essential components. (A) One or two selected from the group of epoxy groups, carboxy groups and hydroxyl groups used in the present invention
Examples of acrylic elastomers having more than one type of functional group include Arontak S-1511L and S-
1511X, S-1015, S-1017 (manufactured by Toagosei Kagaku Co., Ltd.,
(Product name), AR-51 (manufactured by Nippon Zeon Co., Ltd., Product name),
Noxtite PA-501, PA-502 (manufactured by Nippon Mectron Co., Ltd., product name), Teisan Resin WSO23,
Examples include SG51, SG80, and SG90 (manufactured by Teikoku Kagaku Sangyo Co., Ltd., trade name), and these may be used alone or in a mixture of two or more. This acrylic elastomer may have a functional group such as an epoxy group, a carboxyl group, or a hydroxyl group, but among these, those having an epoxy group are particularly used because they react at low temperatures. The amount of this acrylic elastomer blended is preferably 30 to 70% by weight based on the resin component [(A)+(B)+(C)+(D)] of the adhesive composition. If the amount is less than 30% by weight, the flexibility will be poor, and if it exceeds 70% by weight, the flexibility will be improved but the soldering heat resistance and flame retardance after humidification will be poor, which is not preferable. Examples of the polyparavinylphenol resin (B) used in the present invention include Maruzen Resin M, Maruzen Resin MB (manufactured by Maruzen Oil Co., Ltd., trade name), and these may be used alone or in combination depending on the desired flame retardancy.
Use by mixing more than one species. Polyparavinylphenol resin has a molecular structure similar to thermoplastic polystyrene resin, and is also called paraoxystyrene resin, but it has excellent crosslinkability with epoxy resins due to the action of the hydroxyl group at the para position. (B) The blending amount of polyparavinylphenol resin is
It is desirable that the equivalent ratio [(b)/(c)] between the phenolic hydroxyl group (b) and the epoxy group (c) of the epoxy resin (c) is within the range of 0.5 to 7.0. If this equivalence ratio is less than 0.5, the soldering heat resistance after humidification will decrease, and if it exceeds 7.0, the adhesiveness will decrease and the heat deterioration resistance will be poor, which is not preferable. Bromination is carried out by introducing a brominated polyparavinylphenol resin, a brominated epoxy resin, or both, and the bromination rate is preferably 8% by weight or more based on the resin component of the adhesive composition. . This is because if the amount is less than 8% by weight, the effect on flame retardancy will be small. The epoxy resin (C) used in the present invention is not particularly limited, and all epoxy resins can be used.
Examples include bisphenol A type epoxy resins, novolak epoxy resins, and brominated epoxy resins thereof, and these may be used alone or in combination of two or more. Examples of the polyester urethane resin (D) used in the present invention include Pandex F-5102S, T-
5201, T-5205, T-5265, T-5210 (manufactured by Dainippon Ink and Chemicals, trade name), etc., and these may be used alone or in combination of two or more. It is believed that the polyester urethane resin takes a sea-island structure in the adhesive composition after curing, softens the hardness of the epoxy resin, and improves impact resistance. In the case of an adhesive composition for a flexible printed wiring board, it has been found that the hardness is alleviated and that it has a remarkable effect particularly on improving heat deterioration resistance. The blending amount of the polyester urethane resin is preferably 0.5 to 5.0% by weight based on the resin component of the adhesive composition. If the amount is less than 0.5% by weight, there is no effect on heat deterioration resistance, and if it exceeds 5.0% by weight, moisture resistance and adhesive strength will decrease, which is not preferable. Examples of the effect accelerator (E) used in the present invention include dicyandiamide, Epicure YPH-201 (manufactured by Yuka Ciel Epoxy Co., Ltd., trade name), imidazole complex AC-4B series of BF ₃ (manufactured by Maruzen Sekiyu Co., Ltd., trade name ), imidazole, etc., and these can be used alone or in combination of two or more. Crosslinking of epoxy resin is also carried out by paravinylphenol resin and acrylic elastomer, so depending on the molding conditions, a curing accelerator for the epoxy resin may not be necessary, but molding can be carried out at low temperatures for a short time. For this purpose, it is necessary to use a curing accelerator. The amount to be added is determined depending on the molding conditions employed or the desired shelf life. Examples of the inorganic filler (F) used in the present invention include ultrafine anhydrous silica and aluminum hydroxide, which may be used alone or in combination of two or more. The inorganic filler has the effect of adjusting surface tack (adhesion) and mitigating expansion and contraction of the adhesive composition at high temperatures such as during soldering. The blending amount of the inorganic filler is 3% based on the solid content of the adhesive composition.
Preferably it is ~65% by weight. If the amount is less than 3% by weight, the surface tackiness will be strong and processability will be poor, and if it exceeds 65% by weight, the coating properties with the base thin material will be poor and the adhesion will be reduced, which is not preferable. Examples of solvents for adhesive compositions containing the above components as essential components include methyl ethyl ketone, acetone,
Toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, dioxane, methyl cellosolve acetate and mixtures thereof can be used. The adhesive composition is dissolved in a solvent and applied in a solution state, but the resin component before being dissolved can be prepared by mixing the respective raw materials or by proceeding with preliminary curing. The lamination of the synthetic resin thin material and the metal foil via the adhesive composition is achieved by applying the adhesive composition in a solution state to at least either the synthetic resin thin material or the metal foil, and then drying it in a hot air oven. A method can be adopted in which the solvent is volatilized or preliminary curing is performed, and then heat and pressure bonding is performed using a hot press. Alternatively, any method can be adopted, such as continuously coating and drying, then continuously passing through heated rolls, heat-pressing, winding, and post-heat curing. Examples of thin synthetic resin materials include polyimide films and ultra-thin laminates, and examples of metal foils include copper foil, aluminum foil, nichrome foil, and the like. On the other hand, in order to use the solution for adhering a coverlay film, apply the solution to a thickness of 15 to 35 μm on the surface of a thin synthetic resin material using an ordinary coating device, dry it to volatilize the solvent, or use a preliminary coating. Perform curing. Thereafter, it is stacked on a wiring board after forming a pattern to match the flexible printed wiring board, and is bonded and laminated by heating and pressing at a temperature of 150 to 180°C and a pressure of 20 to 40 kg/cm ² . [Examples of the Invention] Next, the present invention will be specifically explained using Examples. In Examples and Comparative Examples, "part" means "polymerization part". Example 1 Acrylic elastomer SG90 (manufactured by Teikoku Kagaku Sangyo Co., Ltd., trade name) was mixed with methyl ethyl ketone/toluene =
400 parts of a 25% solution dissolved in a 1/1 mixed solvent,
50 parts of 60% toluene solution of YDB-400 (manufactured by Toto Kasei Co., Ltd., trade name), 28.8 parts of Epikote 828 (manufactured by Yuka Ciel Epoxy Co., Ltd., trade name), polyester urethane resin T-5205 (manufactured by Dainippon Ink & Chemicals Co., Ltd.) , trade name) 3.2 parts, brominated polyparavinylphenol resin Maruzen Resin MB (manufactured by Maruzen Sekiyu Co., Ltd., trade name)
38 parts, Kyuazol C17Z (manufactured by Shikoku Kasei Co., Ltd., trade name) 1.66 parts, H-43M (manufactured by Showa Light Metal Co., Ltd., trade name)
Weigh and prepare 10.6 parts of methyl cellosolve, 160 parts of methyl cellosolve, and 118 parts of dioxane, stir thoroughly with a high-speed stirrer, and filter through a 100-mesh wire mesh to produce a flexible printed wiring board with a bromine content of 16 to 17% by weight in the resin component. An adhesive solvent solution was prepared. Next, Kapton with a thickness of 50 μm (manufactured by DuPont,
Apply the above adhesive solution to a polyimide film (trade name) to a thickness of approximately 22 μm after drying,
It was dried at 100°C for 5 minutes and then at 150°C for 2 minutes.
After that, a 35μm electrolytic copper foil (manufactured by Fukuda Metal Industry Co., Ltd.) was placed on the adhesive-applied surface, and laminated using a hot press at a press temperature of 160±2℃, a pressure of 30Kg/cm ² , and a heating time of 60 minutes. Then, a flexible printed wiring board was manufactured. The peel strength of the obtained substrate, adhesion after heat deterioration, soldering heat resistance, and flame retardance were tested. The results are shown in Table 1, and the effects of the present invention were confirmed. Comparative Example 1 An adhesive solution and adhesive solution were prepared under the same conditions as in Example 1, except that the polyester urethane resin Pandex T-5205 (described above) was not added and 30.4 parts of Epikote 828 was used as the epoxy resin. A flexible printed wiring board substrate using the above was manufactured. Next, various tests similar to those in Example 1 were conducted, and the results are shown in Table 1.

[Table] Example 2 Acrylic elastomer AR-51 (manufactured by Nippon Zeon Co., Ltd., trade name) was mixed with methyl ethyl ketone/toluene =
360 parts of a 25% solution dissolved in a 1/1 mixed solvent,
25 parts of a 60% toluene solution of YDB-400 (manufactured by Toto Kasei Co., Ltd., trade name), 14.4 parts of Epicote 828 (manufactured by Yuka Ciel Epoxy Co., Ltd., trade name), 1.6 parts of polyester urethane resin Pandex T-5210 (mentioned above), Maruzen Resin MB (manufactured by Maruzen Sekiyu Co., Ltd., trade name) 19 parts, AC
-4B50 (manufactured by Maruzen Oil Co., Ltd., trade name) 0.84 parts, H-
Weighed 90 parts of 43M (manufactured by Showa Light Metal Co., Ltd., trade name), 3 parts of Aerosil 200 (manufactured by Nippon Aerosil Co., Ltd., trade name), 200 parts of methyl cellosolve acetate, 100 parts of ethyl cellosolve, and 100 parts of dioxane.
Prepare, stir thoroughly with a high-speed stirrer, filter through a 100-mesh wire mesh, and reduce the bromine content in the resin component to 11 to 12.
A weight percent adhesive solvent solution was prepared. Next, Kapton with a thickness of 25 μm (manufactured by DuPont,
Apply the above adhesive solution to a polyimide film (trade name) to a thickness of approximately 35 μm after drying,
It was dried at 120°C for 5 minutes and then at 150°C for 2 minutes.
Next, a UL standard V-0 Kapton base copper clad board (copper foil 35 μm) was placed on the shear side of the etched copper foil for evaluation, and a hot press was used to press at a temperature of 160 ± 2°C and a pressure of 40 kg. /cm ² and a heating time of 20 minutes. The obtained coverlay coating was tested for peel strength, adhesion after heat deterioration, solder heat resistance, flame retardancy, solder resistance after humidification, and line insulation resistance.The results are shown in Table 2. Indicated. Example 3 Acrylic elastomer SG-80 (manufactured by Teikoku Kagaku Sangyo Co., Ltd., trade name) was mixed with methyl ethyl ketone/toluene.
300.3 parts of a 20% solution dissolved in a 1/1 mixed solvent,
Arontak S-1015 (manufactured by Toagosei Kagaku Co., Ltd., trade name) 9 parts, Epicoat 282 (mentioned above) 3.5 parts, polyester urethane resin Pandex T-5201 (mentioned above)
2.0 parts, Maruzen Resin MB (mentioned above) 27 parts, dicyandiamide 1 part, Epicure YPH-201 (manufactured by Yuka Ciel Epoxy Co., Ltd., trade name) 0.25 parts, H-43M
Weighed and prepared 152.34 parts of (previously mentioned), 300 parts of methyl cellosolve, 200 parts of dioxane and 289 parts of methyl ethyl ketone, and thoroughly stirred with a high-speed stirrer.
An adhesive solution having a bromine content of 12 to 13% based on the resin component was prepared by filtration through a 100-mesh wire mesh. Next, the adhesive solution was applied to Kapton (mentioned above) with a thickness of 25 μm so that it would have a thickness of about 35 μm after drying, and after drying at 120°C for 5 minutes and further at 150°C for 2 minutes, the adhesive solution was applied to UL standard V. -0 Kapton base copper clad board (copper foil 35μm) was placed on the shear side of the etched copper foil for evaluation, and heated using a hot press at a pressing temperature of 170±2℃ and a pressure of 40Kg/cm ² . Lamination was performed for 45 minutes and coverlay coating was performed. The obtained coverlay coating was tested for peel strength, adhesion after heat deterioration, solder heat resistance, flame retardancy, solder resistance after humidification, line insulation resistance, and processability. Shown in the table. Comparative Example 2 In Example 2, Maruzen Resin MB (mentioned above)
An adhesive solution was prepared and laminated under the same conditions as in Example 2, except that 8.95 parts of phenol novolac resin TD-2093 (manufactured by Dainippon Ink & Chemicals, Inc., trade name) was substituted for 19 parts. The coverlay coating thus obtained was subjected to the same tests as in Example 2, and the results are shown in Table 2. Comparative Example 3 Except that 90 parts of H-43M (mentioned above) and 3 parts of Aerosil 200 (mentioned above) were not added in Example 2,
An adhesive solution was prepared and laminated under the same conditions as in Example 2. The coverlay coating thus obtained was tested in the same manner as in Example 2, and the results are shown in Table 2.

【table】

Examine the presence or absence of abnormalities in [Table] *2: ○ Good × Bad [Effects of the invention] As explained above, the adhesive composition for flexible printed wiring boards of the present invention has excellent adhesive properties, heat deterioration resistance, and flame retardancy. It is an adhesive composition that has excellent properties such as solder resistance after humidification, and insulation resistance between lines, and has good processability when used for coverlays, and is suitable for use in flexible printed wiring boards due to its good balance of properties. It is.

Claims (1)

[Claims] 1 (A) an acrylic elastomer having one or more functional groups selected from the group of epoxy groups, carboxyl groups, and hydroxyl groups, (B) polyparavinylphenol resin, (C) An adhesive composition for a flexible printed wiring board, comprising as essential components an epoxy resin, (D) a polyester urethane resin, (E) a curing agent accelerator, and (F) an inorganic filler. 2 Resin component of adhesive composition [(A)+(B)+(C)+(D)]
The adhesive composition for a flexible printed wiring board according to claim 1, which contains (A) acrylic elastomer in an amount of 30 to 70% by weight, and (D) polyester urethane resin in an amount of 0.5 to 5.0% by weight. 3 (B) Phenolic hydroxyl group equivalent of phenolic resin
Claim 1 or 2, wherein the equivalent ratio [(b)/(c)] between (b) and the epoxy group equivalent (c) of the epoxy resin (C) is within the range of 0.5 to 7.0. Adhesive composition for flexible printed wiring boards. 4. The adhesive composition for a flexible printed wiring board according to any one of claims 1 to 3, which contains 3 to 65% by weight of (F) an inorganic filler based on the solid content of the adhesive composition. . 5. The adhesive composition for a flexible printed wiring board according to any one of claims 1 to 4, wherein the bromination rate of the resin component of the adhesive composition is 8% by weight or more.